Drive system for a marine vessel

ABSTRACT

A drive system for a marine vessel. The drive system includes a drive shaft that is rotatable about a drive axis and a motor interconnected with the drive shaft and including a rotor that defines a motor axis that is substantially coaxial with the drive axis. The motor is operable at a motor speed to rotate the drive shaft. An engine has an output shaft interconnected with the drive shaft and is operable at an engine speed to rotate the drive shaft. The output shaft defines an engine axis that is substantially coaxial with the motor axis. A clutch is operable to inhibit the transfer of torque from the motor to the engine when the engine speed is less than a predetermined engine speed without disconnecting the output shaft from the drive shaft. A tiller arm includes a speed control. The speed control is operable to control the engine speed and to control the motor speed.

BACKGROUND

The present invention relates generally to a drive system for a marinevessel. More particularly, the present invention relates to a hybriddrive system for a marine vessel.

Marine vessels (e.g., boats, inflatable rafts, canoes, sailboats,personal watercraft, and the like) generally include an engine thatturns a propeller to propel the vessel through the water. Generally, theengine is an internal combustion engine that combusts fuel to propel thevessel. Many boats employ an outboard engine, which mounts to thetransom of the vessel and extends into the water. The engine turns thepropeller in the water to generate propulsion. Other vessels may employinboard engines in which the engine is disposed within the boat and onlya portion of a driveshaft and the propeller extend into the water. Stillother vessels use an inboard-outboard engine, which combines certainaspects of inboards and outboards. Generally, the engine is disposedwithin the boat and a lower unit containing a drive shaft and variousgears is disposed outside the boat.

While engines are well-suited to propelling vessels in the water, thereare restrictions on the use of engines on some bodies of water. Inaddition, sportsmen often use an electric motor to quietly move theirvessel into a fishing or hunting area. Unfortunately, these electricmotors are separate from the main engine, thus requiring their owncontrol system as well as their own mechanical systems (e.g., lower unitextending into the water, propeller, driveshaft, drive gears, and thelike). In addition, the electric motors are often visually unappealingand provide additional obstructions for fishing and occupy additionalspace within the vessel.

SUMMARY

The present invention provides a drive system for a marine vessel. Thedrive system includes a drive shaft that is rotatable about a driveaxis, and an electric motor interconnected with the drive shaft andincluding a rotor that defines a motor axis that is substantiallycoaxial with the drive axis. The motor is operable at a motor speed torotate the drive shaft. An engine has an output shaft interconnectedwith the drive shaft and is operable at an engine speed to rotate thedrive shaft. The output shaft defines an engine axis that issubstantially coaxial with the motor axis. A clutch is operable toinhibit the transfer of torque from the motor to the engine when theengine speed is less than a predetermined engine speed withoutdisconnecting the output shaft from the drive shaft. A tiller armincludes a speed control. The speed control is operable to control theengine speed and to control the motor speed.

In another aspect, the invention provides a drive system for a marinevessel. The drive system includes a drive shaft that is rotatable abouta drive axis to propel the vessel, and a motor that includes a rotorcoupled to the drive shaft. The motor is operable at a motor speed torotate the drive shaft. An engine that includes an engine ignition iscoupled to the motor rotor and is operable at an engine speed to rotatethe rotor and the drive shaft. The drive system also includes anelectrochemical energy source (e.g., a battery or fuel cell) and acontroller that is operable to control the flow of electrical powerbetween the electrochemical energy source and the motor. A clutch isdisposed between the motor rotor and the engine. The clutch has adeclutched position in which the transfer of torque from the motor tothe engine is inhibited without decoupling the engine and the motorrotor. A switch has a first position in which the engine is operable anda second position which inhibits operation of the engine but enables themotor to be operable. The drive system also includes a tiller arm havinga speed control. The speed control is operable to control the enginespeed when the switch is in the first position and to control the motorspeed when the switch is in the second position. A switch has a firstposition in which the engine is operable, and a second position in whichthe engine ignition is grounded but the motor is operable.

In still another aspect, the present invention provides a drive systemfor a marine vessel. The drive system includes a drive shaft that isrotatable about a drive axis. A motor includes a stator and a rotor thatdefines a motor axis. The rotor is offset from the stator a distancealong the motor axis to define an axial air gap. The drive shaft rotatesin response to rotation of the rotor at a motor speed. An engineincludes an output shaft. The drive shaft and rotor rotate in responseto operation of the engine at an engine speed. A clutch is operable toinhibit the transfer of torque from the motor to the engine and tofacilitate the transfer of torque from the engine to the motor and tothe drive shaft without manipulating any mechanical connection betweenthe motor, the engine, and the drive shaft.

Additional features and advantages will become apparent to those skilledin the art upon consideration of the following detailed description ofpreferred embodiments exemplifying the best mode of carrying out theinvention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a perspective view of a marine vessel with a hybrid outboardmotor;

FIG. 2 is a partially broken away schematic view of the hybrid outboardmotor of FIG. 1;

FIG. 3 is an enlarged schematic view of a portion of the hybrid outboardmotor of FIG. 1;

FIG. 4 is a perspective view of a one-way bearing;

FIG. 5 is a top view of a centrifugal clutch;

FIG. 6 is an enlarged schematic illustration of the motor portion ofFIG. 1 including a centrifugal clutch;

FIG. 7 is an enlarged schematic illustration of the motor portion ofFIG. 1 including a one-way bearing;

FIG. 7 a is an enlarged schematic illustration of the motor portion ofFIG. 1 including another arrangement of the one-way bearing;

FIG. 8 is a schematic diagram of a control system for the hybrid motorof FIG. 1;

FIG. 9 is schematic diagram of another control system for the hybridmotor of FIG. 1; and

FIG. 10 is a schematic diagram of another control system for the hybridmotor of FIG. 1.

Before any embodiments of the invention are explained, it is to beunderstood that the invention is not limited in its application to thedetails of construction and the arrangements of components set forth inthe following description or illustrated in the following drawings. Theinvention is capable of other embodiments and of being practiced or ofbeing carried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof is meantto encompass the items listed thereafter and equivalence thereof as wellas additional items. The terms “connected,” “coupled,” and “mounted” andvariations thereof are used broadly and encompass direct and indirectconnections, couplings, and mountings.

DETAILED DESCRIPTION

With reference to FIG. 1, a marine vessel 10, in the form of a boat, isillustrated as including an outboard engine 15. Vessels 10 of this typeare often used on small lakes and streams for fishing or otheractivities. The outboard engine 15 provides power to move the marinevessel 10 and rotates about a steering axis to steer the vessel 10.While the present invention will be described in detail as it applies toan outboard engine 15 similar to that of FIG. 1, one of ordinary skillwill realize that the invention has other applications. For example,other types of boats or vessels (e.g., canoes, sailboats, runabouts,personal watercraft, etc.) could employ the present invention.Furthermore, the present invention could be used with an inboard engineor an inboard-outboard engine. As such, the description of the inventionas it applies to an outboard engine 15 should not be read as limitingthe invention to only outboard engines 15.

Turning to FIG. 2, the outboard engine 15 of FIG. 1 is shownschematically with a portion of an exterior housing 20 broken away toshow the internal components. The engine 15 includes an upper portion 25that houses two prime movers, and a lower unit 30 that supports apropeller 35 and contains forward/reverse gearing 40 and a portion of adrive shaft 45. The lower unit 30 extends below the water line 50 toallow rotation of the propeller 35 to propel the vessel 10.

The prime movers disposed in the upper portion 25 of the engine are bestshown in FIG. 3 and include an internal combustion engine 55 and anelectric motor 60. The electric motor 60 is positioned beneath theinternal combustion engine 55 and is interconnected with the drive shaft45. The internal combustion engine 55 also interconnects with the driveshaft 45. Thus, operation of the electric motor 60 or the internalcombustion engine 55 can produce rotation of the drive shaft 45 andpropeller to propel the vessel 10. In most constructions, the internalcombustion engine 55 is air-cooled. However, some constructions mayemploy a water-cooled engine. Water is drawn from the body of water thevessel is operating on and is directed up the lower unit 30 to theengine. After cooling the engine, the water returns down the lower unit30 and flows back into the body of water.

The electric motor 60, shown in FIG. 3, is a brushless DC axial air gapmotor that includes a stator 65 and a rotor 70, and may include a motorcontroller 75 (shown in FIG. 9). A motor 60 of this type is sold byBriggs & Stratton Corporation of Milwaukee, Wis. under the trademarkETEK. While other types of motors could be employed, the motor 60described herein occupies a compact space and provides the horsepowerand torque desired to propel the vessel 10 through the water.

The stator 65 fixedly attaches to the exterior housing 20 of theoutboard engine 15 such that it is substantially coaxial with the driveshaft 45. The stator 65 includes a plurality of poles that each includewindings that can be selectively energized to produce the necessarymagnetic fields for motor operation. The stator 65 also includes asubstantially cylindrical opening 80 through its center that allows forthe passage of a motor shaft, if employed, or the drive shaft 45.

The rotor 70 is a substantially disk-shaped component that supports aplurality of permanent magnets 85. The rotor 70 is supported above thestator 65 with the permanent magnets 85 axially spaced from the statorwindings such that as the stator windings are energized, a magneticfield is produced that interacts with the permanent magnets 85 of therotor 70 to produce rotation. The stator windings are energized andde-energized in a particular sequence, at a particular rate, and with aparticular polarity to produce rotation of the rotor 70 in a desireddirection at a desired speed.

In most constructions, a thrust bearing 90 is disposed between the rotor70 and the stator 65 to both position the rotor 70 relative to thestator 65 and to support the axial load (the weight) of the rotor 70during motor operation. FIGS. 3, 6, and 7 schematically illustrate athrust bearing 90 that is suited to the task of supporting the rotor 70.Other constructions may apply other suitable means to separate the rotor70 from the stator 65. For example, one or more bearings generallysupport the drive shaft 45 for rotation. One of these bearings couldinclude thrust-carrying capability such that the bearing supports thethrust load of the rotor 70. In these constructions, the drive shaft 45supports the generator rotor 70 in the desired axial position withoutthe need for a separate thrust bearing 90 between the rotor 70 and thestator 65.

The internal combustion engine 55, illustrated in FIG. 3, includes ahousing 95 that supports one or more piston/cylinder arrangements thatoperate to rotate a crankshaft, as is well known in the engine art. Thenumber of piston/cylinder arrangements employed is largely a function ofthe power required for the particular application. The engine 55combusts an air/fuel mixture to rotate the crankshaft and produce shaftpower. The crankshaft extends from the housing to define an output shaft100. In most constructions, the output shaft 100 extends vertically fromthe bottom of the housing 95 along an engine axis A-A. The engine 55 issimilar to known internal combustion engines and as such will not bedescribed in detail.

Support members 103 engage the engine 55 and the exterior housing 20 tosupport the engine 55 in its desired operating position above theelectric motor 60. As illustrated in FIGS. 2 and 3, the support members103 resemble columns. The actual form of the support members 103 isunimportant so long as they are capable of supporting the engine 55above the motor 60. The support members generally provide no alignmentfunction but rather allow the engine 55 to move as needed to properlyalign the output shaft 100 relative to the drive shaft 45. For example,in one construction a platform is supported by the stator 65 and isshaped to support the engine 55.

The output shaft 100 extends from the bottom of the engine 55 andengages a clutch mechanism 105 between the engine 55 and motor 60. FIGS.2, 3, 5 and 6 illustrate one possible clutch mechanism 105 in the formof a centrifugal clutch 110. The centrifugal clutch 110 includes anouter drum 115, a biasing member 120 (e.g., one or more springs), and aplurality of clutch weights 125. A pocket 130, including cylindricalwalls, is formed in the motor rotor 70 to define the outer drum 115.Forming the outer drum 115 in the motor rotor 70 provides for a morecompact arrangement, while simultaneously reducing the number ofcomponents. The clutch weights 125 are disposed within the drum 115 andare fixedly attached to the output shaft 100 so that they rotate inunison with the shaft 100 but are free to move radially. The clutchweights 125 move radially between a disengaged (declutched) position andan engaged (clutched) position within the pocket 130, with the biasingmember 120 biasing the clutch weights 125 toward the disengagedposition.

The biasing member 120 is sized to produce a biasing force that issubstantially equal to the centrifugal force applied to the clutchweights 125 at a predetermined rotational speed. In some constructions,this predetermined rotational speed is slightly above the idle speed ofthe engine 55 such that when the engine 55 idles, the clutch 110disengages to produce a neutral operating condition. Of course otherconstructions may allow clutch engagement at lower or higher speeds asrequired by the particular application. As the engine 55 accelerates,the rotational speed exceeds the predetermined speed and the centrifugalforce applied to the weights 125 exceeds the force of the biasingmembers 120. Once the centrifugal force exceeds the biasing force, theclutch weights 125 move to the clutched position. In the clutchedposition, the clutch weights 125 frictionally engage the drum 115, orpocket 130, such that the output shaft 100 and the drum 115 (i.e., therotor 70) rotate in unison.

During electric motor operation, the motor rotor 70, and the pocket 130rotate around the clutch weights 125. However, because the output shaft100 does not rotate, no forces are applied to the clutch weights 125. Assuch, the clutch weights 125 cannot engage the cylindrical surface ofthe pocket 130 and instead remain in the disengaged or declutchedposition. Thus, the electric motor 60 does not transfer torque to theinternal combustion engine 55 when the motor rotor 70 is rotating andthe output shaft 100 is stopped or is rotating too slowly to overcomethe biasing force produced by the biasing member 120. The centrifugalclutch 110 allows the engine 55 to rotate both the propeller 35 and themotor rotor 70 when the engine 55 is powering the vessel 10 and inhibitsrotation of the engine 55 when the motor 60 is providing power to thepropeller 35.

FIGS. 4, 7, and 7 a illustrate another possible clutch mechanism 105that is suited for use with the present engine 15. The clutch mechanism105, in the form of a one-way bearing 135 (shown in detail in FIG. 4),is illustrated in FIGS. 7 and 7 a in two possible operating positions.The one-way bearing 135 includes an outer race 140, an inner cage 145,and a plurality of rolling members 150. As illustrated in FIG. 7, theouter race 140 engages the output shaft 100, while the rolling members150 engage a stub shaft 155 that is coupled to the motor rotor 70.During operating conditions in which the stub shaft 155 rotates at ahigher speed than the output shaft 100, the rolling members 150 moveinto a free rolling position. In the free rolling position, the rollingmembers 150 allow relative movement between the stub shaft 155 and theoutput shaft 100. If, on the other hand, the output shaft 100 rotates ata higher speed than the stub shaft 155, the rolling members 150 moveinto a locked position. With the rolling members 150 in the lockedposition, the stub shaft 155 and the output shaft 100 rotate in unison.Thus, the bearing 135 allows torque transfer from the engine 55 to themotor rotor 60 when the output shaft 100 rotates faster than the motorrotor 60. However, the bearing 135 inhibits torque transfer from themotor rotor 70 to the engine 55 when the motor rotor 70 is rotating at ahigher speed than the output shaft 100.

It should be noted that FIG. 7 illustrates a construction in which theouter race 140 of the one-way bearing 135 engages the output shaft 100and the stub shaft 155 engages the rolling members 150. One of ordinaryskill will realize that this arrangement could be reversed such that therolling members 150 engage the output shaft 100 and the outer race 140engages the stub shaft 155.

FIG. 7 a illustrates another construction in which the stub shaft 155 iseliminated. In this construction, the outer race 140 of the one-waybearing 135 engages a bearing pocket 160 formed in the motor rotor 70and the engine output shaft 100 engages the rolling members 150 withinthe bearing 135. This construction has the advantage of reducing thequantity of components needed and further reduces the space occupied bythe engine 55 and motor 60.

While bearings 135 of the type described are available from manysources, one such one-way bearing 135 suited for use with the presentengine 15 is sold by The Timken Company, located in Canton Ohio, asTimken Torrington Drawn Cup Roller Clutch bearings.

As illustrated in FIG. 3, the drive shaft 45 extends the full length ofthe lower unit 30 and engages the rotor 70. Of course, otherconstructions may include two or more shafts that are directly coupledto one another or indirectly connected (e.g., via a belt, a chain, agear, a transmission, and the like). When two or more shafts areemployed, a motor shaft (not shown) engages the rotor 70 such thatrotation of the rotor 70 produces a corresponding rotation of the motorshaft and the drive shaft 45, which is coupled to the motor shaft.Connection of the motor shaft to the rotor 70 may be achieved using manycommon connections, including but not limited to, a spline connection ora keyed connection. Splined and keyed connections provide excellentrotational coupling, while still allowing for some relative axialmovement between the motor shaft and the rotor 70. Thus, exact axialpositioning of the rotor 70 relative to the motor shaft or propeller 35is not necessary.

While a direct drive system has been described (i.e., the drive shaft 45rotates at the same speed as the engine 55 or motor 60), certainapplications may employ a transmission disposed between the internalcombustion engine 55 and/or the motor 60 and the drive shaft 45. Thetransmission may simply allow the engine 55 or motor 60 to be offsetrelative to the drive shaft 45 without changing the rotational speed ofthe drive shaft 45 or may include a speed-reducer or a speed-increaser.For example, it may be desirable to rotate the propeller 35 at a speedthat is substantially faster or substantially slower than the optimalengine or motor speed. In these applications, a speed-increaser or aspeed-reducer could be positioned between the engine 55 and/or motor 60and the propeller 35 to achieve the desired results.

The use of the clutch mechanism 105 as described allows the user toswitch between engine operation and motor operation without disturbingany mechanical connections. Thus, the user is not required to make anymechanical adjustments such as shifting between gears, engaging themotor 60 with a drive gear, or disengaging the engine output shaft 100and the drive shaft 45. Rather, the user moves an electrical switch 170(shown in FIGS. 8 and 9) to transition between the engine 55 and themotor 60. The motor rotor 70, the engine output shaft 100, and the driveshaft 45 remain coupled during all operating modes.

Both the engine 55 and the motor 60 include separate speed input systemsthat allow the user to control the speed of the vessel 10 using a commoninterface. To control the speed of the vessel 10 when operating underengine power, the user adjusts the throttle position as is well known inthe engine art. The outboard engine 15 includes a tiller arm 175 (shownin FIGS. 1 and 2) that has a rotatable handle 180 positioned at one end.The rotatable handle 180 is coupled to a throttle cable such thatrotation of the handle 180 changes the throttle position and varies thespeed of the engine 55. In other constructions, rotation of the handle180 produces axial movement of a throttle cable. The throttle cable isthreaded through the engine 55 and housing 95 to the carburetor throttlecontrol such that the motion of the throttle cable directly adjusts thethrottle position. Typically, the rotatable handle 180 is biased to alow speed or idle position, thereby requiring the operator to rotate andhold the handle 180 in a particular position to maintain the speed ofthe engine 55 above an idle speed.

When operating under motor power, the user controls the speed of theelectric motor 60 and not the engine 55. Rather than provide a separateinterface, the present invention provides a sensor 185 coupled to therotatable handle 180 of the tiller arm 175. The sensor 185 may beintegrated with the throttle control such that rotation of the handle180 not only adjusts the throttle position but also adjusts the sensor185. For example, a rotary potentiometer could be positioned such thatthe movement of the throttle cable produces a corresponding movement ofthe potentiometer. Rotation of the handle 180 would vary the resistanceof the potentiometer (e.g., between 0 and 500 Ohms). The variableresistance is sensed by the controller 75 and is used as a speed setpoint, or is used directly to vary the current provided to the motor 60.For example, a zero Ohm resistance may be representative of a maximumspeed. Thus, when the potentiometer is rotated to the zero Ohm position,the controller 75 drives the motor 60 to its highest rotational speed.Similarly, 500 Ohms may be representative of zero speed. Thus, when thecontroller 75 senses 500 Ohms (or more) of resistance from thepotentiometer, the speed of the motor 60 is reduced to a minimum value(zero RPM). In this manner, rotation of the rotatable handle 180produces a speed control signal that the motor controller 75 can use tocontrol the speed of the motor 60 when the motor 60 is powering thevessel 10.

One of ordinary skill will realize that other devices could be used inplace of the potentiometer. For example, linear or rotary variabledifferential transformers are also well suited to the task of indicatinga desired speed. As such, the present invention should not be limited torotary potentiometers or potentiometers for that matter.

One possible control system suited to powering and controlling theelectric motor 60 is illustrated in FIG. 8. The control system includesthe switch 170, a relay or contactor 190, the sensor 185, and anelectrochemical energy source in the form of a battery 195. The switch170 is generally a double pole switch movable between a “gas” positionand an “electric” position. A first circuit 200 includes the switch 170,a pair of wires, and a portion of the engine ignition system. Thecircuit 200 is controlled by the switch 170 extends from the engine 55and, when closed, grounds the ignition system of the engine 55 toinhibit engine operation. A second circuit 205 also includes the switch170, the contactor 190, and the battery 195. The second circuit 205 iscontrolled by the switch 170 and powers the relay 190 that opens andcloses a contact between the battery 195 and the motor 60. With theswitch 170 in the position illustrated in FIG. 8, the ignition system isnot grounded and is able to provide power to the engine's spark plug. Inaddition, the relay circuit is open such that the power circuit,controlled by the relay 190, remains open and battery power cannottravel to the motor 60. Thus, the illustrated configuration would allowengine operation and inhibit motor operation.

When the switch 170 is moved to the electric position, both the relaycircuit 205 and the engine ignition system circuit 200 close. With theswitch 170 in the closed position, the engine ignition system isgrounded and cannot deliver power to the spark plugs. Thus, the engine55 will not operate. In addition, the closed relay circuit 205 energizesthe relay 190 to close the contact between the battery 195 and the motor60. Thus, power is free to travel from the battery 195 to the motor 60and the motor 60 is able to propel the vessel 10. The sensor 185, (i.e.,the potentiometer) is positioned in the circuit between the motor 60 andthe battery 195 to allow the potentiometer to control the power flow tothe motor 60 and to vary the speed of the motor 60. As discussed, thepotentiometer is connected to the rotatable handle 180 of the tiller arm175 so that a user may rotate the handle 180 to vary the resistance ofthe circuit and the speed of the motor 60.

In another construction illustrated in FIG. 10, the sensor 185 includesa rotary switch rather than a potentiometer. Rotation of the rotatablehandle 180 of the tiller arm 175 opens or closes the rotary switch. Whenthe rotary switch is closed, the motor 60 rotates at a fixed speed andwhen the switch is open, the motor 60 does not rotate. Thus, the user isable to control the speed of the vessel 10 when propelled by the motor60 by rotating the same handle 180 that is rotated when powered by theinternal combustion engine 55.

FIG. 9 illustrates another control system suited for use with thepresent invention. The control system includes the switch 170, thesensor 185, the motor controller 75, and the electrochemical energysource in the form of the battery 195. Many different motor controllers75 can be used to control the motor 60. In addition, because manydifferent types of motors 60 can be used (e.g., brush-type DC motors,brushless DC motors, and the like), different types of controllers 75may be employed. For example, a set of switches and contactors could beused if the motor 60 is a brush-type DC motor. If the motor 60 is abrushless DC motor, a MOSFET-based brushless DC motor control would bewell-suited to controlling the motor 60.

The switch 170 is generally a double pole switch that controls twoseparate circuits. A first, or engine ignition circuit 210, is open whenthe switch 170 is in the “gas” position and is closed when the switch170 is moved to the “electric” position. The ignition circuit 210includes the switch 170, a pair of wires, and a portion of the engineignition system. When the engine ignition circuit 210 is closed, theignition system of the engine 55 is grounded and no electrical power canbe delivered to the spark plug(s) of the engine 55. Thus, engineoperation is inhibited. A second circuit 215 includes the switch 170,and a portion of the controller 75. The second circuit 215 sends acontrol signal to the motor controller 75. When the switch 170 is in the“gas” position, a signal is sent to the motor controller 75 that allowsthe motor controller 75 to function as a power conditioner or regulatorsuch that electricity generated by the engine driven motor 60 can beused to charge the battery 195. When the switch 170 is in the “electric”position, a signal is sent to the controller 75 that indicates that thecontroller 75 is controlling the motor 60.

In other constructions, the second circuit 205 controls a relay as wasdescribed with regard to FIG. 8. In these constructions, the motor 60does not charge the battery 195 when operating under engine power. Instill other constructions, the second circuit 205 is eliminated and thecontroller 75 automatically determines if it should be regulating powerfor delivery to the battery 195 or delivering power to the motor 60 topropel the vessel 10.

When operating under motor power, the controller 75 receives a flow ofDC current from the battery 195. The controller 75 in turn deliverspower to the electric motor 60 via two of three power connectionsbetween the controller 75 and the motor 60. Each of the powerconnections provides power to a distinct winding within the stator 65.The power provided by the controller 75 is provided to the particularwindings in a particular order, at a particular rate, and with aparticular polarity to produce a rotating magnet field within the stator65. The permanent magnets 85 of the rotor 70 react to the rotatingmagnetic field by rotating. Thus, by controlling the rate at which therotating magnetic field rotates, the controller 75 is able to controlthe rotary speed of the motor 60.

One or more Hall devices or Hall sensors 220 are positioned adjacent therotor 70 to sense the actual rotary position of the rotor 70. The Hallsensors 220 send signals to the controller 75 indicating the actualposition of the rotor 70 to allow the controller 75 to refine thecontrol of the motor 60 and accurately maintain the desired rotor speed.

As discussed, the motor controller 75 can also function as a voltageregulator to charge the battery 195 when the internal combustion engine55 is operating and the motor 60 is idle. When operating under engine 55power, the internal combustion engine rotates the rotor 70 withoutcurrent being provided to the stator windings. The permanent magnets 85on the rotor 70 induce an electrical current in the windings that flowsto the controller 75. The controller 75 conditions the power such thatit can be delivered to the battery 195 to charge the battery 195.

In use, either the internal combustion engine 55 or the electric motor60 can power the vessel 10. In one mode, a user employs the internalcombustion engine 55 to move the vessel 10 toward a desired location. Touse the internal combustion engine 55, the switch 170 is positioned inthe fuel position and the engine 55 is started. Once started, theinternal combustion engine 55 provides power to the propeller 35 androtates the motor rotor 70 to charge the battery 195. As the userapproaches the desired location, the internal combustion engine 55 canbe shut off and the switch 170 can be moved to the electric position. Inthe electric position, the switch 170 grounds the engine's ignition toinhibit the combustion process. In addition, the controller 75 providespower to the electric motor 60, thereby allowing the motor 60 to propelthe vessel 10. The clutch mechanism 105 inhibits rotation of the engine55 as the electric motor 60 moves the vessel 10 around the desiredlocation.

In the application just described, the electric motor 60 would generallybe smaller (output less power) than the internal combustion engine 55.For example, a twenty horsepower internal combustion engine may be usedwith a five horsepower motor. In other applications, equal powerinternal combustion engines and electric motors are used. In still otherapplications, large electric motors are used with relatively smallinternal combustion engines.

The present invention can be manufactured as a single unit or ascomponents that can be applied to pre-existing outboard motors. Whenmanufactured as components, the electric motor 60 and controller 75 aregenerally provided for attachment to a pre-existing internal combustionengine, such as illustrated engine 55. The engine 55 is decoupled fromthe drive shaft 45 and removed. The electric motor 60 is placed in theposition previously occupied by the engine 55 and the motor 60 iscoupled to the drive shaft 45. The support members 103 are positioned asnecessary to support the engine 55 above the motor 60. The engine 55 isrepositioned above the motor 60 and the engine output shaft 100 iscoupled, via the clutch mechanism 105, to the motor rotor 70. In thisway, an internal combustion engine is converted to a hybridcombustion-electric propulsion system.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe scope and spirit of the invention as described and defined in thefollowing claims.

1. A drive system for a marine vessel, the drive system comprising: adrive shaft rotatable about a drive axis; a motor including a rotor thatdefines a motor axis, the drive shaft rotating in response to rotationof the rotor at a motor speed; an engine including an output shaft, thedrive shaft and rotor rotating in response to operation of the engine atan engine speed; a clutch operable to inhibit the transfer of torquefrom the motor to the engine and to facilitate the transfer of torquefrom the engine to the motor and to the drive shaft without manipulatingany mechanical connection between the motor, the engine, and the driveshaft; and a tiller arm including a speed control, the speed controloperable to control the engine speed and to control the motor speed. 2.The drive system of claim 1, wherein the motor includes a stator, andwherein the rotor is spaced axially from the stator to define an axialair gap.
 3. The drive system of claim 1, wherein the motor rotor isinterconnected with the drive shaft such that the motor rotor rotates inunison with the drive shaft.
 4. The drive system of claim 1, wherein theclutch connects the output shaft and the motor rotor.
 5. The drivesystem of claim 1, wherein the clutch includes a clutched position and adeclutched position and wherein the clutch is in the declutched positionwhen the engine speed is below a predetermined speed and is in theclutched position when the engine speed is above the predeterminedspeed.
 6. The drive system of claim 1, wherein the clutch includes acentrifugal clutch.
 7. The drive system of claim 1, wherein the clutchincludes a roller clutch.
 8. The drive system of claim 1, wherein atleast a portion of the clutch is formed as part of the rotor.
 9. Thedrive system of claim 1, further comprising a switch having a firstposition in which the engine is operable, and having a second positionin which operation of the engine is inhibited but the motor is operable.10. The drive system of claim 9, wherein the engine includes an engineignition that is grounded when the switch is in the second position. 11.The drive system of claim 9, wherein the engine operates when the switchis in the first position to rotate the motor rotor and the drive shaft,the rotation of the motor rotor delivering a flow of electrical currentto an electrochemical energy source, and wherein when the switch is inthe second position the electrochemical energy source delivers a flow ofelectrical current to the motor such that the motor operates to rotatethe drive shaft.
 12. The drive system of claim 9, wherein the speedcontrol is operable to control the engine speed when the switch is inthe first position and to control the motor speed when the switch is inthe second position.
 13. The drive system of claim 9, further comprisinga power conditioner interconnecting the motor and an electrochemicalenergy source, the power conditioner operable to deliver conditionedpower to the electrochemical energy source when the switch is in thefirst position and to deliver an amount of conditioned power to themotor when the switch is in the second position.
 14. The drive system ofclaim 1, wherein the speed control includes a potentiometer.
 15. A drivesystem for a marine vessel, the drive system comprising: a drive shaftrotatable about a drive axis to propel the vessel; a motor including arotor coupled to the drive shaft, the motor operable at a motor speed torotate the drive shaft; an engine including an engine ignition, theengine coupled to the motor rotor and operable at an engine speed torotate the rotor and the drive shaft; an electrochemical energy source;a controller operable to control the flow of electrical power betweenthe electrochemical energy source and the motor; a clutch disposedbetween the motor rotor and the engine, the clutch operable both toinhibit the transfer of torque from the motor to the engine and tofacilitate the transfer of torque from the engine to the motor and tothe drive shaft without decoupling the engine and the motor rotor; and aswitch having a first position in which the engine is operable, andhaving a second position in which the engine ignition is grounded butthe motor is operable.
 16. The drive system of claim 15, wherein themotor includes a stator, and wherein the rotor is spaced axially fromthe stator to define an axial air gap.
 17. The drive system of claim 15,wherein the motor rotor is interconnected with the drive shaft such thatthe motor rotor rotates in unison with the drive shaft.
 18. The drivesystem of claim 15, wherein the engine includes an engine drive shaftand the clutch connects the engine drive shaft and the motor rotor. 19.The drive system of claim 15, wherein the clutch includes a centrifugalclutch.
 20. The drive system of claim 15, wherein the clutch includes aroller clutch.
 21. The drive system of claim 15, wherein at least aportion of the clutch is formed as part of the rotor.
 22. The drivesystem of claim 15, wherein the engine operates when the switch is inthe first position to rotate the motor rotor and the drive shaft, therotation of the motor rotor delivering a flow of electrical current tothe electrochemical energy source, and wherein when the switch is in thesecond position the electrochemical energy source delivers a flow ofelectrical current to the motor such that the motor operates to rotatethe drive shaft.
 23. The drive system of claim 15, wherein thecontroller is operable to deliver conditioned power to theelectrochemical energy source when the switch is in the first positionand to deliver an amount of conditioned power to the motor when theswitch is in the second position.
 24. The drive system of claim 15further comprising a tiller arm including a speed control, the speedcontrol operable to control the engine speed when the switch is in thefirst position and to control the motor speed when the switch is in thesecond position.
 25. The drive system of claim 24, wherein the speedcontrol includes a motor speed adjustment member that is movable betweena first position and a second position to provide a signal to thecontroller to vary the amount of electrical power delivered to themotor.
 26. The drive system of claim 25, wherein the motor speedadjustment member includes a potentiometer.
 27. A drive system for amarine vessel, the drive system comprising: a drive shaft rotatableabout a drive axis; a motor including a stator and a rotor that definesa motor axis, the rotor offset from the stator a distance along themotor axis to define an axial air gap, the drive shaft rotating inresponse to rotation of the rotor at a motor speed; an engine includingan output shaft, the drive shaft and rotor rotating in response tooperation of the engine at an engine speed; and a clutch operable toinhibit the transfer of torque from the motor to the engine and tofacilitate the transfer of torque from the engine to the motor and tothe drive shaft without manipulating any mechanical connection betweenthe motor, the engine, and the drive shaft.
 28. The drive system ofclaim 27, wherein the motor rotor is interconnected with the drive shaftsuch that the motor rotor rotates in unison with the drive shaft. 29.The drive system of claim 27, wherein the clutch connects the outputshaft and the motor rotor.
 30. The drive system of claim 27, wherein theclutch includes a clutched position and a declutched position andwherein the clutch is in the declutched position when the engine speedis below a predetermined speed and is in the clutched position when theengine speed is above the predetermined speed.
 31. The drive system ofclaim 27, wherein the clutch includes a centrifugal clutch.
 32. Thedrive system of claim 27, wherein the clutch includes a roller clutch.33. The drive system of claim 27, wherein at least a portion of theclutch is formed as part of the rotor.
 34. The drive system of claim 27,further comprising a switch having a first position in which the engineis operable, and having a second position in which operation of theengine is inhibited but the motor is operable.
 35. The drive system ofclaim 34, wherein the engine includes an engine ignition that isgrounded when the switch is in the second position.
 36. The drive systemof claim 34, wherein the engine operates when the switch is in the firstposition to rotate the motor rotor and the drive shaft, the rotation ofthe motor rotor delivering a flow of electrical current to anelectrochemical energy source, and wherein when the switch is in thesecond position the electrochemical energy source delivers a flow ofelectrical current to the motor such that the motor operates to rotatethe drive shaft.
 37. The drive system of claim 34, further comprising atiller arm including a speed control, the speed control operable tocontrol the engine speed when the switch is in the first position and tocontrol the motor speed when the switch is in the second position. 38.The drive system of claim 37, wherein the speed control includes a motorspeed adjustment member movable between a first position and a secondposition, the motor speed adjustment member providing a signal to thepower conditioner to vary the amount of conditioned power delivered tothe motor.
 39. The drive system of claim 38, wherein the speedadjustment member includes a potentiometer.
 40. The drive system ofclaim 34, further comprising a power conditioner interconnecting themotor and an electrochemical energy source, the power conditioneroperable to deliver conditioned power to the electrochemical energysource when the switch is in the first position and to deliver an amountof conditioned power to the motor when the switch is in the secondposition.